What is the opening size of a 250*90 buried lamp?
The plane didn't mark you look at the chart diagram of distribution system, look at the floor there is no distribution box, if there is cable distribution box distribution box, distribution box of BV line to line lamp.
Correct your point of view, the bridge can not be done in the underground, buried cable through the cable well, through the buried pipe into the distribution room, the bridge with the earth does not matter. You may have just started this scene, you have no count!! Try running more,
General indoor cable from the distribution box is out of the bridge, go to a certain position in the bridge from both sides of the hole line to the lamp.If the floor is small, you can use the BV line directly from the distribution box through the bridge line.
